What is the recommended post-exposure prophylaxis (PEP) regimen for a patient exposed to Human Immunodeficiency Virus (HIV)?

HIV Post-Exposure Prophylaxis

Initiate bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) as a single tablet once daily for 28 days immediately after HIV exposure, starting within 1-2 hours if possible, but no later than 72 hours post-exposure. 1, 2, 3

Preferred Regimen

The CDC recommends BIC/FTC/TAF (bictegravir 50mg/emtricitabine 200mg/tenofovir alafenamide 25mg) as the first-line PEP regimen. 1, 2, 3 This single-tablet formulation maximizes adherence and has superior renal and bone safety compared to older regimens. 1

Alternative Regimen if BIC/FTC/TAF Unavailable

• Dolutegravir (DTG) 50mg once daily PLUS emtricitabine/tenofovir alafenamide (FTC/TAF) 200mg/25mg once daily for 28 days 1, 2, 3
• You may substitute tenofovir disoproxil fumarate (TDF) 300mg for TAF if TAF is unavailable, though TAF is preferred due to better renal safety 1, 2
• You may substitute lamivudine (3TC) 300mg for emtricitabine if needed 1, 3

Critical Timing Requirements

Do not delay the first dose for any reason—efficacy decreases dramatically with each passing hour. 1, 2, 3

• Initiate PEP as soon as possible, ideally within 24 hours of exposure 1, 3
• Maximum window is 72 hours; after this, efficacy drops significantly 1, 2, 3
• Do not wait for laboratory results or source patient testing before starting the first dose 1, 3
• If the source is later confirmed HIV-negative during the 28-day course, you can stop PEP 1

Baseline Assessment Before First Dose

Perform these tests immediately but do not delay the first PEP dose while awaiting results: 1, 3

• Rapid or laboratory-based HIV antigen/antibody combination test 1, 2, 3
• Add HIV nucleic acid test (NAT) if the patient received long-acting injectable PrEP in the past 12 months 1, 3
• Baseline renal function (creatinine, eGFR) before any tenofovir-based regimen 1, 2
• Review current medications for potential drug interactions 1, 2, 3
• Assess for medical comorbidities and allergies 1, 3

Duration and Adherence

Complete the full 28-day course regardless of subsequent information about the source patient. 1, 2, 3

• Incomplete adherence significantly reduces effectiveness 1, 3
• The single-tablet BIC/FTC/TAF regimen improves completion rates compared to multi-pill regimens 1

Follow-Up Testing Schedule

• Within 72 hours after starting PEP: Clinical evaluation and assessment for drug toxicity 1, 2, 3
• Monitor for at least 2 weeks: Ongoing toxicity monitoring 1, 2
• At 4-6 weeks: HIV antigen/antibody test PLUS HIV nucleic acid test (NAT) 1, 2, 3
• At 12 weeks: Laboratory-based HIV antigen/antibody combination immunoassay AND HIV nucleic acid test (NAT) 1, 2, 3

Special Populations

Renal Impairment

• Use tenofovir alafenamide (TAF) instead of tenofovir disoproxil fumarate (TDF) for patients with impaired renal function 1, 2, 3
• TAF has improved renal and bone safety profiles compared to TDF 1

Pregnancy

• Pregnancy does not preclude the use of optimal PEP regimens and should not be a reason to deny PEP 2
• Expert consultation is advised for pregnant patients 2

Common Pitfalls to Avoid

Never prescribe only two NRTIs (like tenofovir/emtricitabine alone) for PEP—this provides inadequate protection and requires a third drug (integrase inhibitor). 1

• Never delay initiation beyond 72 hours, as effectiveness drops significantly 1, 2, 3
• Never use salvage therapy agents (fostemsavir, ibalizumab) for PEP—these are reserved for treatment-experienced patients with documented resistance 1
• Do not fail to assess for potential drug interactions with concurrent medications 1, 2, 3
• Consider different regimens if the patient has a history of antiretroviral exposure 1

Counseling Requirements

• Advise the exposed person to use precautions to prevent secondary transmission during the follow-up period 2, 3
• Instruct the patient to seek immediate medical evaluation for any acute illness during follow-up, as this may indicate acute retroviral syndrome 4, 2

Transition to PrEP After Completing PEP

• Consider immediate transition from PEP to PrEP for persons with anticipated repeat or ongoing HIV exposures 1, 3
• Perform HIV testing at completion of the 28-day PEP course before transitioning to PrEP 1, 3

Expert Consultation Resources

For complex cases, contact the National Clinicians' Post-Exposure Prophylaxis Hotline (PEPline) at 1-888-448-4911, but do not delay PEP initiation while awaiting consultation. 2

Evidence Supporting Current Recommendations

The shift from older regimens (zidovudine/lamivudine-based) to integrase inhibitor-based regimens reflects substantial improvements in tolerability and completion rates. Research demonstrates that dolutegravir-based regimens achieve 90% completion rates 5, significantly higher than older protease inhibitor-based regimens (39-57% completion) 6. The single-tablet BIC/FTC/TAF formulation further optimizes adherence by reducing pill burden. 1 While older CDC guidelines from 2001 recommended zidovudine/lamivudine as the basic regimen 4, these have been superseded by current recommendations prioritizing integrase inhibitors due to superior efficacy, tolerability, and adherence profiles.